And how to you measure the torque such that tightening is to specification.

190E 2.6 1993
I replaced the v-belt and water pump at the same time and now the v-belt (although the tensioner is turned to the correct mark) seems to still be little loose. I'm not sure how tight it should be but compared to my other cars it seems a little loose. The belt also makes and an occassional high pitched noise like it may be skippping.

What is the normal running temperature in Celsius?
Mine is running at just above 80. but when idling with the AC on it is closer to 100C with the auxillary fan on.
Could this be related to the belt tension. Visual inspection reveals that the belt is tuning the pulley appropriately. (the water pump is aftermarket and not Mercedes benz).